Notable publications

Notable publications

Congratulations to Daniel Gomez et al from CSIRO and Ion Beam Group, who recently published Waveguide-Plasmon Polariton Enhanced Photochemistry in Advanced Optical Materials. The paper looked at a key process in plasmon-enhanced photocatalysis, light absorption by metal nanostructures followed by the transfer of hot charge-carriers from metal nanostructures into photocatalytically active materials. This study focused on 1D gratings of metal wires and found strong enhancements in the rate of decomposition, exhibiting a correlation with the measured optical extinction spectra of the plasmonic nanostructures.

Congratulations to Hongzhou Zhang et al from Trinity College Dublin, Deakin University, King Saud University and Beijing Institute of Technology, who recently published Nanopatterning and Electrical Tuning of MoS Layers with a Sub-Nanometre Helium Ion Beam in Nano Letters. This work focused on helium-ion microscopy, which is not only emerging as a high-resolution tool for materials imaging, but is also capable of highly accurate nanopatterning and nanofabrication. The results demonstrated the ability of ion beams in helium-ion microscopes to be effective nanofabrication tools for two-dimensional nanomaterials such as MoS2 and oxides, and potentially also graphene, phosphorene and layered transition metal carbides.

Congratulations to Qiaoliang Bao et al from Soochow University, Hong Kong Polytechnic University, Monash University and Wuhan University, who recently published Highly responsive MoS2 photodetectors enhanced by graphene quantum dots in Scientific Reports. Molybdenum disulphide (MoS2) is an attractive material for optoelectronic and photodetection applications because of its tunable bandgap and high quantum luminescence efficiency, however issues around light absorption and gain mechanics have prevented MoS2-based photodetectors from further improvement. In this study, the researchers demonstrate a photoresponsivity of approximately 104 AW-1 and a photogain of approximately 107 electrons per photon in an n-n heterostructure photodetector that consists of a multilayer MoS2 thin film covered with a thin layer of graphene quantum dots (GQDs). The enhanced light-matter interaction results from effective charge transfer and the re-absorption of photons, leading to enhanced light absorption and the creation of electron-hole pairs.

Congratulations to Ranjith Rajasekharan et al from the University of Melbourne and Humboldt-Universitat zu Berlin, who recently published Micro-concave waveguide antenna for high photon extraction from nitrogen vacancy centers in nanodiamond in Scientific Reports. In order to make practical devices using nanodiamond, highly efficient and directional emission of single photons in well-defined modes, either collimated into free space or waveguides are essential. This is a Herculean task as the photoluminescence of the NV centers is associated with two orthogonal dipoles arranged in a plane perpendicular to the NV defect symmetry axis. In this study, the research team report on a micro-concave waveguide antenna design which can effectively direct single photons from any emitter into either free space or into waveguides in a narrow cone angle with more than 80% collection efficiency irrespective of the dipole orientation. The device also enhances the spontaneous emission rate, which further increases the number of photons available for collection. The waveguide antenna has potential applications in quantum cryptography, quantum computation, spectroscopy and metrology.

Congratulations to Mainak Majumder et al from Monash University and CSIRO, who recently published Miniaturized Supercapacitors: Focused Ion Beam Reduced Graphene Oxide Supercapacitors with Enhanced Performance Metrics in Advanced Energy Materials. In this study, focused ion beam (FIB) technology was used to directly write miniaturized planar electrode systems of reduced graphene oxide on films of graphene oxide. The results may provide avenues for large-scale fabrication of arrayed, planar, high-performance micro-supercapacitors with a small environmental footprint.

$200 MCN credits up for grabs for correct acknowledgements in publications

MCN & ANFF acknowledgement in publications

MCN Users can receive a $200 facility credit per article when they correctly acknowledge MCN and ANFF in published works and advise MCN’s Communications Officer within 30 days of publication.

The MCN access and pricing policy requires that all academic publications arising from the use of MCN subsidised facility time must acknowledge both MCN and ANFF. For reference, the correct acknowledgement reads as follows: “This work was performed in part at the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the Australian National Fabrication Facility (ANFF)”.

If your paper fits the bill, email the link to mcn-enquiries@nanomelbourne.com within 30 days of publication in order to claim your credit.

June – what a month!

June at MCN

June was a huge month, with a record number of users working at MCN. 129 users from 19 organisations logged 2,835 hours over the month, keeping the cleanroom busy and our staff on their toes. As a multi-institutional facility, we are happy to see figures like these showing that the spirit of collaboration and innovation is alive and well in Victoria.

"It is fantastic to see the investment in shared infrastructure can be concurrently accessible to so many different organisations," said MCN Director Dwayne Kirk.

If you would like to learn more about accessing the world-class facilities available at MCN, click here. 

MCN at National Manufacturing Week

News_May15_NMW_gallery

National Manufacturing Week (NMW) will be taking place next week at the Melbourne Convention Centre from 26-29 May 2015. NMW is the only fully integrated annual manufacturing exhibition showcasing the latest products and constantly evolving technologies in the expanding manufacturing market.

Following the success of the NMW Solutions Theatres in 2014, NMW 2015 will feature a fantastic program of free education and networking, showcase two unique free-to-attend theatres on the exhibition floor, including the R&D Hub, and Digital Solutions Theatre. The R&D hub will showcase new ideas in manufacturing design and technology and will aim it is to bridge the gap between innovation and development.

MCN’s booth (number 5410) will be situated nearby the R&D hub – we encourage you to drop past, chat to our expert staff and inspect MCN’s new displays which feature a range of processes including, DRIE, EBL holographic shims, diamond deposition, optical profilometry, 3D printing and more.

 

A collaborative space for start-ups

The Monash Enterprise Centre
A seminar room in the Monash Enterprise Centre

The Monash City Council have recently opened the Monash Enterprise Centre, a collaborative space for start-ups and entrepreneurs who wish to commercialise their innovative ideas. The centre rents rooms and fully furnished office suites for small businesses who are starting out. It provides meeting rooms, reception services, office resources and kitchen facilities to tenants, providing a professional work space at affordable rates.

Due to the collaborative nature of the centre, networking opportunities allow business to benefit from each others' services, expertise and experience. There will also be regular learning workshops and access to training seminars specific to small businesses.

If you think this could benefit you, visit the website for more information or to make an inquiry.

Artificial leaves enhance light to energy conversion

Left: SEM image of the top view of a fabricated artificial leaf (light harvesting structures), where the white bar corresponds to a length of 200 nm. Right: Diagram illustrating the artificial leaves and the size scales involved.  Credit: D. Gomez

Modern society is, to a very large extent, built on the products of the organic chemical industry. On a daily basis, these products are used for making pharmaceuticals, plastics, health and cosmetics products and for several items in the housing, transportation and telecommunication industries.

However, the chemical industry relies heavily on fossil fuel derived energy for carrying out these chemical processes. A more sustainable and desirable prospect is to harvest sunlight for doing chemistry and thus transform this industry into a solar chemical manufacturing industry.

This project aims to create novel ways to harvest solar energy for driving chemical reactions instead of generating electrical power. To this end, a team of researchers from CSIRO and the National Institute for Materials Science design in Japan, have fabricated nano-sized structures that are capable of harvesting light and converting it into chemical potential energy.

They have used the high-resolution electron beam lithography tool at MCN to create structures capable of efficiently harvesting light for driving chemical transformations, with some assessment of their performance carried out by collaborators in Japan. The artificial leaves, or light harvesting devices, are made out of a light harvesting components in direct contact with an electron filter. Each element is made of aluminum wires with a cross section of tens of nanometers. The spacing between the light harvesting elements is a critical parameter, with its magnitude is in the hundreds of nanometers, which is controlled with a 10nm resolution.

Through this project the team have demonstrated up to two orders of magnitude improvement in the rate of the chemical reaction of a test model using their light-harvesting system. They have achieved this by using a very simple configuration of nanostructures and anticipate that more spectacular light-to-chemical energy transformations can be achieved with more sophisticated nanoparticle deigns.

The team is currently creating more sophisticated nanoparticle systems that are capable of absorbing nearly 100% of the incident light across the visible spectrum. This will translate into much higher light-to-chemical energy transformation efficiencies and they envisage that these light-harvesting technologies could be used for developing a sustainable and solar driven fine chemicals manufacturing industry in the not too distant future.

We’re hiring!

Marketing & Communications Officer

MCN is currently looking for a Marketing and Communications Officer. The successful candidate will have excellent written communication skills and strong attention to detail, exceptional organisational skills, a strong sense of creativity and design, as well as analytical and problem‑solving skills.

Key selection criteria include:

1.  A degree in a relevant field OR experience in public relations, marketing, communications or similar, OR an equivalent combination of relevant experience and/or education/training.

2. Proven, high-level written and oral communication and interpersonal skills with proven experience in writing articles, corporate communications and technical information for websites and brochures for a variety of audiences.

3. Highly competent computer literacy skills including experience with the Adobe Creative Suite, web content management (ideally wordpress), electronic direct mail programs (ideally mailchimp) and the ability to acquire skills in the use of new software packages.

4. Highly competent research, creative design, analytical and problem-solving skills including a demonstrated capacity to show initiative and take responsibility for a broad range of activities and functions as well as develop solutions to complex problems.

5. Highly effective work organisation skills including the ability to plan, prioritise tasks, work effectively under pressure, achieve goals within established timelines and changing priorities and operate in a methodical manner paying particular attention to detail.

6. Project management experience, specifically the ability to organize and coordinate events and logistics.

7. Proven ability to liaise, consult and negotiate with clients both internal and external and at all levels.

More details can be found here.

Applications close Thursday 21 May 11:55pm AEST

Noteworthy publications

Figure 1: Experimental and simulated extinction spectra of NC nanosheets. Inset are the optical microscopy images and TEM images of individual plasmene nanosheets.
Figure 2: Fabrication process of the strain sensors.
Figure 3: Photographs of a strain sensor ring attached on the little finger while bending (scale bar: 1 cm). The inset is the top-view scanning electron microscope (SEM) image of the AuNWs film on latex rubber substrate.
Figure 4: a) Plan view and cross-sectional schematics of a-STO cross bar MIM structures, where three types of a-STO were investigated. b) Arrhenius-type plots for virgin state conduction activation energy under a 100 mV bias.
Figure 5: a) Schematic configuration of graphene–perovskite phototransistor. b) Transfer curves of transistor devices based on graphene and graphene–perovskite. Inset shows the energy diagrams before and after graphene being in contact with perovskite.
Figure 6: (a–c) AFM height and phase, and KPFM surface potential images of atomically flat MoS2 after 5 h air exposure. Inset in (a) shows the optical image of the MoS2 crystal. (g–i) AFM height, phase, and surface potential images of the MoS2 crystal after air exposure for 3 days.

Congratulations to MCN Technology Fellow Professor Wenlong Cheng and colleagues who published “Ultrathin Plasmene Nanosheets as Soft and Surface-Attachable SERS Substrates with High Signal Uniformity” in Advanced Optical Materials. The paper builds on work published in the article Giant Plasmene Nanosheets, Nanoribbons, and Origami and looks at ultrathin plasmene nanosheets as a new class of flexible SERS substrates capable of conformal attachment. They can also be used for the sensitive and reproducible detection of chemicals on topologically complex surfaces. (see figure 1) 

Congratulations to MCN Technology Fellow Professor Wenlong Cheng and colleagues who published “Highly Stretchy Black Gold E-Skin Nanopatches as Highly Sensitive Wearable Biomedical Sensors” in Advanced Electronic Materials. The paper presents a micron thin and highly stretchable strain sensor for human health and motion monitoring. The technology is based on a stretchable latex rubber with flexible black gold nanowires patches and the fabrication strategy can be extended to a variety of soft substrates and exhibits high sensitivity. (see figures 2 + 3) 

Congratulation to Hussein Nili et al from RMIT University and the University of California Santa Barbara who published “Donor-Induced Performance Tuning of Amorphous SrTiO3 Memristive Nanodevices: Multistate Resistive Switching and Mechanical Tunability” in Advanced Functional Materials. The paper looks at metal–oxide valence-change memristive devices which are the key contenders for the development of multilevel nonvolatile analog memories and neuromorphic computing architectures. Reliable low energy performance and tunability of nonlinear resistive switching dynamics are essential to streamline the high-density circuit level integration of these devices. This paper looks at manipulation of room temperature-synthesized defect chemistry to enhance and tune the switching characteristics of high-performance amorphous SrTiO3 (a-STO) memristors. These results highlight the potential of donor-doped a-STO nanodevices for high-density integration as analog memories and multifunctional alternative logic elements. (see figure 4) 

Congratulations to MCN Technology Fellow Dr Qiaoliang Bao and colleagues who published “Hybrid Graphene–Perovskite Phototransistors with Ultrahigh Responsivity and Gain” in Advanced Optical Materials. The paper looks at graphene, which is an attractive optoelectronic material for light detection because of its broadband light absorption and fast response time. However, its relatively low absorption cross-section, fast recombination rate, and the absence of gain mechanism have limited the responsivity of pure graphene-based phototransistors. In this work, a photoconductive gain is demonstrated in a hybrid photodetector that consists of monolayer graphene covered with a thin layer of dispersive organolead halide perovskite islands. The unprecedented performance is attributed to the effective charge transfer and photogating effect, which are evidenced by photoluminescence quenching, time-resolved photoluminescence decay, scanning near-field optical microscopy, and photocurrent mapping. (see figure 5) 

Congratulations to Changxi Zhen et al from Monash University, National Institute for Materials Science Japan, FUNSOM and Soochow University who published “Profound Effect of Substrate Hydroxylation and Hydration on Electronic and Optical Properties of Monolayer MoS2” in Nano Letters. The paper highlights the use of AFM, Kelvin probe force microscopy and scanning photoluminescence spectroscopy to image the progressive postgrowth hydroxylation and hydration of atomically flat Al2O3(0001) under monolayer MoS2. This manifested in large work function shifts due to charge transfer from the substrate and changes in PL intensity, energy, and peak width. In contrast, trapped water between exfoliated graphene and Al2O3 causes surface potential and doping changes one and two orders of magnitude smaller, respectively, and MoS2 grown on hydrophobic hexagonal boron nitride is unaffected by water exposure. (see figure 6) 

Internship program begins a second semester

MCN Intern, Lachlan Pierce at work using the ALD Fiji F200 in the MCN Cleanroom

Following the success of the current industrial internship program, which saw four interns partnered with industry clients to accomplish short term nanofabrication projects, MCN is now seeking expressions of interest from industry partners and interns for participation in this year’s Fabrication Internship Program. This iteration of the program aims to assist our industry clients in meeting engineering challenges with specific alignment to MCN’s core fabrication facilities, whilst also providing valuable work experience for program interns.

Key features of the program include MCN covering the cost of a full-time intern for industry partners in the program, while participants are also able to enjoy a 50% discount on all MCN instrumentation, including the staff time required for intern training, for the length of the project. Partners will retain all IP input and output from the project deliverables and will be able to select interns from a pool of highly capable bachelors and master engineering and physics interns.

Interns will benefit professionally from the project leadership experience and will have the opportunity to work with some exciting companies at the forefront of nanofabrication development. They will develop their own skill sets through direct technical and operation support from MCN staff and industry partners and will be involved in real-life projects which hold great impact for Victoria’s fabrication and engineering economies.

MCN is seeking expressions of interest from industry partners as well as intern candidates from May 2015. The program is due to start in July 2015. 

Students who are eligible to work in Australia and who are interested in applying for the program should send their CV and a cover letter outlining their skills and experience to internship@nanomelbourne.com.

Industry partners interested in discovering how the internship program could benefit your projects, please fill in the expression of interest form and email it to internship@nanomelbourne.com.

Diamond systems produce shining results

SEM of a high quality diamond film grown at MCN. 

LEED pattern from a moderately boron doped diamond grown in the 6300 tool. The very sharp primary spots and very low background show a high crystalline quality surface (smooth). Right: Cross-sectional confocal fluorescence image, showing a very low fluorescence epi-layer of diamond which is grown on top of a medium/high fluorescence diamond substrate.

MCN’s twin Seki diamond deposition systems have been in operation for almost 12 months, after being launched by Minister Pyne last May. In that time, they have been utilised for some exciting projects by the MCN and University of Melbourne tool experts who have developed a series of effective recipes and growths.

Included in this is the growth of extremely high quality boron doped diamond as well as ultra-pure growth diamond.

Samples of boron doped diamond have been grown with high surface quality and good conductivity for surface-science. Samples of this quality and utility are incredibly difficult to source in the diamond community, and while being tested, these samples have already enabled significant publishable results. The image in above (left) shows a LEED pattern captured at the Australian Synchrotron, where a very high quality surface, with low background scattering and sharp features was observed. The combination of smooth surface and moderate doping levels enabled low temperature measurement in a combination of synchrotron techniques (x-ray absorption, photoelectron and work-function studies).

Significant results have also been achieved in the growth of ultra-pure diamond. This was demonstrated using a 10um thick epi-layer grown at MCN, which was then measured using a confocal fluorescence microscope capable of imaging single fluorescent defects in the layer. With a low fluorescence epi-layer on top, a high quality of diamond is demonstrated. Of note, preliminary scans within the epi-layer have identified an average fluorescent defect concentration of less than one defect per 100um3 volume, which represents a bulk concentration of less than 1 part per trillion.

For more information, please contact Lachlan Hyde.